Remember this is unsupported. You would probably be better off waiting until vRA 7 is released to see if they introduce a supported version of this.
In the IaaS SQL DB navigate to the table "DynamicOps.RepositoryModel.WorkflowDefinitions" find the row with the name "ReconfigureVMGeneric" set the field "IsProtected' to 0. Flipping that from 1 to 0 will make it visible to the vRA Designer application. Open up designer, edit the reconfigure workflowStub to add a step to call out to a vRO workflow (you can look at the other workflowstubs that were modified by vRO to provide extensibility). After that the generic native "Reconfigure" button will call out to that vRO workflow.